Russia has banned a pro-democracy charity founded by hedge fund billionaire George Soros, saying the organization posed a threat to both state security and the Russian constitution.

In a statement released Monday morning, Russia's General Prosecutor's Office said two branches of Soros' charity network — the Open Society Foundations (OSF) and the Open Society Institute (OSI) — would be placed on a "stop list" of foreign non-governmental organizations whose activities have been deemed "undesirable" by the Russian state.

George Soros

"It was found that the activity of the Open Society Foundations and the Open Society Institute Assistance Foundation represents a threat to the foundations of the constitutional system of the Russian Federation and the security of the state," a translated version of the press statement read.

Soros, who is best known for his namesake Soros Fund Management firm, originally founded the OSF network to help countries transition from communism. The charity now funds project aimed at democracy building across the globe.

OSF first came into trouble with the Russian government in July, when it hinted it might ban the foundation along with a number of other pro-democracy organizations accused of launching "soft aggression" in the country.

The billionaire also came under fire in his Hungarian homeland in October when state politicians accused Soros and his charity of supporting illegal migration. OSF had criticized Hungary's' treatment of refugees while the billionaire suggested migrants receive $16,000 per year to help cover housing, healthcare and education costs.

OSF was not able to provide comment when contacted by CNBC but said it was preparing a statement.